The present invention relates to a mask fabrication method and a technique for fabricating a semiconductor integrated circuit device, and more specifically to a technique effectively applied to mask fabrication to transfer desired patterns onto a semiconductor wafer.
Generally, masks used in an exposure technique each have a structure of providing, on a mask blank transparent to exposure light, a light-shielding pattern made from a metal film such as chrome. An example of the manufacturing process includes the following. First of all, a metal film made from light-shielding chrome etc. is deposited on the transparent mask blank, and an electron beam sensitive resist film is coated thereon. Subsequently, an electron beam is illuminated to a specified location of the electron beam sensitive resist film by an electron beam writer etc., and this illuminated resist film is developed to form a desired resist pattern. At this time, there is the case in which a resist pattern (defect) other than the desired resist pattern may be formed. Thereafter, by using, as an etching mask, the resist pattern formed on the mask blank to etch the lower metal film, a desired light-shielding pattern made from a metal film is formed. At this time, light-shielding film defect is also formed by a resist pattern other than the desired resist pattern. Then, after removing the left resist pattern, presence or absence of the defect is determined by carrying out defect inspection. If any defect is detected, for example, a laser beam or ion beam is irradiated to the detected defect to remove it. Subsequently, after a mask without defect is prepared through a washing step, a protection pellicle is mounted on a main surface (surface on which a desired light-shielding pattern is formed) so that no fault by adhesion of foreign matters occurs. A half-tone type phase-shift mask is also fabricated in almost the same process by simply replacing the metal film with a half-tone phase-shift film.
Furthermore, for the purpose of simplifying the process and forming the pattern with a high degree of accuracy, a method of forming a light-shielding film by a resist film is disclosed, for example, in Japanese Patent Laid-open No. 5-289307. This method utilizes such a property that a normal electron beam sensitive resist film or light-sensitive resist film shields vacuum ultraviolet radiation with a wavelength of 200 nm or lower. According to this method, a metal-film etching process or resist-film removing process is made unnecessary, whereby it is possible to reduce manufacturing costs of the mask, improving dimensional accuracy, and reduce a quantity of defect (for example, see Patent Document 1). Additionally, also with respect to defect repair, a method of using a regular laser beam or a FIB (Focused Ion Beam), etc. is disclosed.
[Patent Document 1]
Japanese Patent Laid-open No. 5-289307